Rapistrum Rugosum Research Articles

Response of Some Pepper Genotypes to Cucumber Mosaic Virus (CMV) and Discrimination of Kilis Isolates Using High-Resolution Melting (HRM) Method

The escalating global population, diminishing agricultural lands, and the overarching global climate crisis are significantly impacting pepper cultivation. These challenges exacerbate the vulnerability of pepper plants to various biotic and abiotic factors, particularly viral diseases, resulting in diminished yield and quality. Cucumber mosaic virus (CMV), a notable concern for peppers in the Solanaceae family, is causing substantial quality and yield losses, with no effective chemical control methods currently available. This study focuses on exploring the genetic structure of CMV isolates obtained from pepper production areas in Kilis province and comparing these regions through the High-Resolution Melting (HRM) method. CMV isolates, cultivated in tobacco plants, have their partial coat protein sequences compared with those of other CMV isolates registered in the gene bank. The nucleotide sequences of identified CMV isolates are phylogenetically grouped and compared using an HRM graph. The HRM graph effectively distinguishes Kilis 3 and Kilis 4 isolates, clustered similarly to sequence patterns, from other isolates. The study highlights the utility of HRM analyses in identifying differences between isolates before determining sequence patterns. In the gene bank comparison, Kilis CMV isolates distinguished from others. Similarities were observed with isolates from Iran's Balsam (Impatiens balsamina - LC066478), Türkiye's Radish (Raphanus sativus - LC0665051), and Wild Turnip (Rapistrum rugosum - LC066514, LC066511, LC066517). The study found that Kilis 7 CMV isolate, transferred mechanically to 24 different pepper genotypes (C. annuum) from the local population, revealed susceptibility to CMV in the 24 lines developed from the Elbeyli population in Kilis province.

Emergence Pattern of Argemone mexicana, Brassica tournefortii, and Rapistrum rugosum in Eastern Australia

A study assessed the potential for using cumulative growing degree days (CGDD) to predict the weed emergence periodicity of three weed species: Argemone mexicana, Brassica tournefortii, and Rapistrum rugosum. Weed emergence was monitored regularly by placing 200 fresh seeds of each weed species on the soil surface. Weed emergence data was fit using a three-parameter sigmoidal Gompertz model. The CGDD required for 50% emergence of A. mexicana ranged from 3380 to 5302, depending upon the seasonal variation in temperature and rainfall. The majority of emergence appeared from March to June. The seeds of A. mexicana exhibited dormancy, as the majority of seeds germinated in the second season. The CGDD required for 50% emergence of B. tournefortii ranged from 824 to 2311, depending upon the seasonal variation in temperature and intensity of rainfall. Most cohorts of B. tournefortii appeared in the first season from February to June, indicating little dormancy in seeds. The CGDD required for 50% emergence of R. rugosum ranged from 2242 to 2699, depending upon weather parameters (temperature and rainfall). The main cohorts of R. rugosum appeared from February to June, and 60% of seeds germinated in the first season, while 40% germinated in the second season, indicating dormancy in seeds. The coefficients of determination for the model verification on the emergence pattern of three weeds were > 85%, suggesting that CGDD are good predictors for the emergence of these weeds. These results suggest that forecasting the emergence of three weed species on the basis of CGDD and rainfall patterns will help growers to make better weed management decisions.

Effect of the tillage system on the floristic composition and the emergence of weeds in Allium sativum

In fragile environments, no-tillage (0T) instead of conventional tillage (CT) is desirable to prevent agroecosystem degradation, but there is little information on its implementation in horticulture. This study aimed to investigate the effects of replacing CT with 0T on floristic composition and weed emergence dynamics in a garlic crop, under the hypothesis that the implementation of a 0T system alters the weed community during the initial stage of the transition. Two experiments were carried out following a randomized complete block design with two treatments (garlic crop grown under 0T and CT). In two subsampling per plot, biweekly destructive weed surveys were carried out. Although both tillage systems presented a similar diversity between systems, these weed communities varied by 36% in their species identity, and it was recorded a higher total weed density under CT (P>0.05). Under 0T, anemophilous Asteraceae, such as Conyza bonariensis and Sonchus oleraceus, tended to increase their presence. Under CT, there was a greater amount of indehiscent fruiting Brassicaceae such as Raphanus sativus and Rapistrum rugosum. The implementation of Vicia villosa as a predecessor crop led to many births due to its capacity for natural reseeding. It is concluded that there are important changes in the species composition and weed emergence patterns immediately after the implementation of 0T compared to CT, suggesting that the filtering pressures exerted by each tillage system favor certain weed species over others. By understanding weed community shifts and critical stages of weed emergence, farmers can improve herbicide application, thereby reducing the excessive use of chemicals and minimizing environmental impact. In addition, this information can help to schedule labor and machinery more efficiently, saving time and production costs.

Interference of Brassicaceae weeds (Brassica tournefortii, Rapistrum rugosum, and Sisymbrium thellungii) in chickpea

AbstractAfrican mustard (Brassica tournefortii Gouan), turnipweed [Rapistrum rugosum (L.) All.], and African turnipweed (Sisymbrium thellungii O.E. Schulz) are common broadleaf weeds in chickpea (Cicer arietinum L.) crops, particularly under dryland region conditions in eastern Australia. Information on crop yield losses and the seed production potential for these weeds in chickpea are limited. Field studies were conducted in the winter seasons of 2020 and 2021 in eastern Australia with different densities of the three weeds (B. tournefortii, R. rugosum, and S. thellungii) in chickpea. Based on the sigmoidal model, chickpea yield was reduced by 50% at 11 plants m−2 of B. tournefortii. Based on hyperbolic models, a 50% yield reduction of chickpea occurred at 5 and 25 plants m−2 of R. rugosum and S. thellungii, respectively. Based on the linear model, B. tournefortii, R. rugosum, and S. thellungii produced a maximum of 448,000, 206,700, and 869,400, seeds m−2, respectively. At chickpea harvest, the low seed retention (<55%) of B. tournefortii and S. thellungii suggests limited opportunities for harvest weed seed control, and the seed rain of these weeds may enrich the weed seedbank in the soil. At crop harvest, the seed retention of R. rugosum was found to be greater than 90%, suggesting that it is a suitable candidate for harvest weed seed control. This study demonstrated that R. rugosum could cause a greater reduction in chickpea yield compared with B. tournefortii and S. thellungii. Furthermore, restricting seed rain of B. tournefortii and S. thellungii by not allowing the plants to produce seeds is recommended to reduce their weed seedbanks in the soil. The information generated from this study could aid in strengthening integrated weed management in chickpea.

Cucumber mosaic virus and turnip mosaic virus occurrence in garlic mustard in Ukraine

Garlic mustard (Alliaria petiolata) is an herbaceous biennial plant native to Europe. In Ukraine, in addition to becoming a serious invader, garlic mustard can serve as a host to several viruses, which may affect agricultural crops. In view of this, the purpose of the study was to identify the virome of garlic mustard growing in Ukraine. Plant samples collected in Kyiv regions were tested for the presence of cucumber mosaic virus (CMV), turnip mosaic virus (TuMV), turnip yellow mosaic virus (TYMV), watermelon mosaic virus II (WMV), and turnip crinkle virus (TCV) by serological and/or molecular methods. According to the results found in the present study, symptomatic A. petiolata obtained in 2021 were infected with CMV (60%), TuMV (20%), or co-infected with CMV + TuMV (20%). TYMV, WMV II, and TCV were not detected in any of the collected samples. The cDNA fragments encoded the coat protein (CP) gene of CMV and TuMV were sequenced and named as CMV-Ap and TuMV-Ap, respectively. In phylogenetic analysis, the CMV-Ap closely resembled the German isolate MW582807 (Sarracenia sp.), with 99.8% nucleotide identity and belongs to subgroup II of CMV. In the phylogenetic tree, TuMV-Ap clustered with isolates AP017803, AP017764, AP017791, and JQ073722, and represented the highest identity (98.6%) to Iranian isolate IRNTRa9 (AP017803) from Rapistrum rugosum and Turkish isolate TUR49 (AP017872) from Raphanus raphanistrum. The sequences of CMV-Ap and TuMV-Ap were deposited in the GenBank under Accession Numbers MZ540213 and OM799323, respectively. The results obtained in the study indicate the important role of infected garlic mustard as alternative host and natural reservoir of CMV and TuMV from which these economically important viruses can spread to other wild and cultivated plants. This is the first molecular evidence of TuMV infection in A. petiolata from Ukraine.

The critical periods of weed control on the weed species composition, morphological, physiological, and biochemical characteristics responses of black seed (Nigella sativa L.)

A field experiment was conducted to the determine the critical period of weed control and its effect on the weed composition, the yield components, seed yield, oil yield, oil content, and the major secondary metabolites accumulation in the black seed (Nigella sativa L.). Two treatment series: weed-free (WF) and weed-infested (WI) periods, were performed from the seed emergence of the black seed until its maturity. The plots were kept weed-free for 0, 14, 28, 42, 56 and 70 days after emergence of the black seed and vice versa. In the weed community composition, 19 species from 14 families were recorded in the studied experimental field. Among the weeds, the Poaceae family (5) had the highest number of species, followed by the Fabaceae family (2). The major species were Avena sterilis L., Rapistrum rugosum L. (All), and Convolvulus arvensi L. during the harvesting of black seed. Results also revealed that the seed yield, yield components, seed oil content, and oil yield of the black seed significantly decreased due to the longer periods of WI or shorter periods of WF. In this study, weed-black seed competition periods promoted the total alkaloid and total phenolic accumulation, compared to WI periods, which indicated the plant's defensive response against the stress caused by the weeds. However, the decrease in seed yield and oil content indicates the insufficient levels of these compounds to cope with the weed stress. This study also concluded that the highest seed yield was obtained by keeping the plots WF from 42 or 70 days after emergence of the black seed to prevent yield loss higher than 10%. Therefore, this period could be the critical period of WF in the black seed.

New floristic records from Central Europe 11 (reports 149-163)

The presented 11th part of the series includes 15 new records of vascular plants from Hungary, Slovakia and Ukrainian Carpathians. In Hungary, second country record of Rapistrum rugosum, Amaranthus emarginatus subsp. emarginatus and Pyrus betulifolia were reported. In Slovakia, new localities of Lathyrus hirsutus and seven alien Euphorbia maculata, Nigella damascena, Geranium macrorrhizum, G. purpureum, Pseudofumaria lutea, Ruta graveolens and Salvia sclarea were recorded. Guizotia abyssinica and Lupinus angustifolius are new aliens for the flora of Slovakia. From the Ukrainian Carpathians new findings of Arabidopsis neglecta and Scorzoneroides pseudotaraxaci were recorded. URL: https://www.upjs.sk/pracoviska/botanicka-zahrada/odborne-aktivity/contents-abstracts/

Taxonomical and chorological notes 17 (178–183)

Floristical records of two lichen-forming fungi and four flowering plants are presented from Hungary. The rare lichen-species Gyalecta fagicola now is known from 7 localities in Hungary with 5 new records. Polyblastia philaea a terricolous lichen species is new to Hungary. The first confirmed record (Szentendre) of the annual weed Adonis annua, a new occurrence (Bodrog bank, Sárospatak) of Cyperus michelianus in the upper Tisza region, and a new locality of the alien weed Rapistrum rugosum from Szentendre (Bizottság-liget) are reported. The naturalised weed Polycarpon tetraphyllum has a stable, spreading population in Budapest with several thousands of individuals.

Freezing stress affects the efficacy of clodinafop-propargyl and 2,4-D plus MCPA on wild oat (Avena ludoviciana Durieu) and turnipweed [Rapistrum rugosum (L.) All.] in wheat (Triticum aestivum L.).

The occurrence of freezing stress around herbicides application is one of the most important factors influencing their performance. This experiment was performed to evaluate the efficacy of clodinafop-propargyl and 2,4-D plus MCPA (2,4-Dichlorophenoxyacetic acid plus 2-methyl-4-chlorophenoxyacetic acid), the most important herbicides used in wheat fields in Iran, under the influence of a freezing treatment (-4°C). Wheat and its two common weeds, winter wild oat (Avena ludoviciana Durieu) and turnipweed [Rapistrum rugosum (L.) All.], were exposed to the freezing treatment for three nights from 7:00 P.M. to 5:00 A.M. before and after herbicide application, and their response was compared with plants that did not grow under freezing stress. Under no freezing (NF) and freezing after spray (FAS) conditions, winter wild oat was completely controlled with the recommended dose of clodinafop-propargyl (64 g ai ha-1; hereafter g ha-1). However, the survival percentage of winter wild oat in the freezing before spray (FBS) of clodinafop-propargyl 64 g ha-1 was 7%, and it was completely controlled with twice the recommended dose (128 g ha-1). Under NF conditions and FAS treatment, turnipweed was completely controlled with twice the recommended dose of 2,4-D plus MCPA (2025 g ae ha-1; hereafter g ha-1), while there was no complete control under recommended rate. However, in the FBS treatment, the survival of turnipweed was 7% under double dose. The LD50 (dose required to control 50% of individuals in the population) and GR50 (dose causing 50% growth reduction of plants) rankings were NF<FBS<FAS for clodinafop-propargyl and NF<FAS<FBS for 2,4-D plus MCPA. Selectivity index for clodinafop-propargyl in NF conditions, FBS, and FAS treatments was 2.4, 0.91, and 0.78, respectively, and, for 2,4-D plus MCPA, it was 2.6, 0.12, and 0.88, respectively. According to the results of LD50, it can be stated that the freezing stress after the spraying of clodinafop-propargyl and before the spraying of 2,4-D plus MCPA would further reduce the efficacy of these herbicides.

Development and reproductive potential of Plutella xylostella (Lepidoptera: Plutellidae) in five Brassicaceae hosts

Plutella xylostella (L.) is one of the main pests in Brassicaceae crops, although, information regarding its biology on alternative hosts is scarce, crucial for its mass rearing. We studied the development, biology, and population parameters of P. xylostella, fed with different Brassicaceae. In laboratory conditions, P. xylostella was reared from larva 1 to adult. Larvae were fed with B. napus (rapeseed), Brassica carinata (Ethiopian rape), Brassica oleracea var. capitata (cabbage), Rapistrum rugosum (turnipweed) and Raphanus raphanistrum (radish). The development time of immature stages was longer in B. oleracea var. capitata (19.19 ± 0.43d) and shorter in R. raphanistrum (15.44 ± 0.37d). In R. rugosum, the highest survival of individuals that reached adult stage was achieved. The highest value of oviposited eggs was recorded in R. rugosum (300.82 ± 24), and highest hatching percentage in R. raphanistrum (79.7%). The highest values of net reproductive rate, intrinsic rate of increase and finite rate of growth, were obtained with R. rugosum. P. xylostella complete their whole cycle in any of the five hosts, being R. rugosum most suitable host for an efficient mass rearing system.

Pollen Micromorphological Study of Ten Genera of Brassicaceae in West Iraq Desert

This research included a micromorphological study of pollen grains of 11 taxa belonging to 10 plant genera of the Cruciferae family (Brassicaceae) distributed in Western Desert District of Iraq. The pollen grains of all species were monads, homopolar, regular, in addition to being tricolpate. They differed in shape, ranging from prolate, subprolate and Subprolate-subspheroidal. The polar dimension also differed greatly among species, which ranged between 25.2 μm. as an average in Morettia philaeana to 37.3 μm. as an average in Zilla spinosa. Thus, the equatorial dimension ranged between 21.4-30.1 μm. in the two species Leptaleum filifolium and Rapistrum rugosum respectively. As for the remaining species, they are graded between them. The difference in the length of the colpus resulted in important taxonomic characteristics in isolating species, if its length ranged between isolating 13.8 -30.3 μm. The Apocolpium also contributed through the variance that ranged between 3.9-8.6 μm., as well as the mesocolpium, which also varied between species, the shortest was 7.2 μm. in Morettia philaeana and the longest 18.3 μm. in Myagrum perfoliatum as indicated in the measurement tables. The two species, Eruca vesicaria and Strigosella africana are distinguished by their thin pollen walls (1.3 μm.), while Morettia philaeana had a thick wall (2.7 μm.), and then the reamining species came between them. This study identified two types of Ornamentation, namely, Microreticulate in 7 species and Macroreticulale in 4 species.

Ecological Niche Shifts Affect the Potential Invasive Risk of Rapistrum rugosum (L.) All. in China.

Ecological niche is a key concept that links species distributions. Ecological niche shifts are expected to affect the potential invasive risk of alien species. Rapistrum rugosum is an invasive agricultural weed in many countries. Wild populations of R. rugosum have been recorded in China, representing a great threat to the regional crops. Based on distribution records from different regions and relevant environmental variables, the present study predicted the potential distribution and estimated the invasive risk of R. rugosum in China. Ecological niche shifts strongly affected the potential invasive risk of R. rugosum in China. The two most important variables were annual temperature range (Bio7) and mean temperature of the coldest quarter (Bio11). The total suitable habitat for the species covered an area of 287.53 × 104km2 and was mainly distributed in Southwest, Southeast, and Central China. Australia, Canada, Brazil, the United States, and Argentina accounted for over 90% of the inspection records of R. rugosum from Chinese entry ports during 2015–2018. The intercepted R. rugosum was frequently mixed in Glycine max (L.) Merr., Hordeum vulgare L., linseed, Triticum aestivum L., and Sorghum bicolor (L.) Moench. Moreover, 80% interceptions were recorded from Tianjin, Guangdong, Nanjing, and Chengdu customs. Climatic conditions do not limit the establishment capability of R. rugosum in China. Our results provide a theoretical reference for the development of monitoring and control measures for this invasive weed.

Rapistrum rugosum

This datasheet on Rapistrum rugosum covers Identity, Distribution, Hosts/Species Affected, Biology &amp; Ecology, Further Information.

Seedbank persistence and emergence pattern of Argemone mexicana, Rapistrum rugosum and Sonchus oleraceus in the eastern grain region of Australia

A thorough understanding of the emergence pattern and persistence of weed seeds is a prerequisite in framing appropriate weed management options for noxious weeds. In a study conducted at the University of Queensland, Australia, the emergence and seed persistence behavior of three major weeds Sonchus oleraceous, Rapistrum rugosum, and Argemone mexicana were explored with seeds collected from Gatton and St George, Queensland, Australia, with an average annual rainfall of 760 and 470 mm, respectively. Seed persistence was evaluated by placing seeds at the surface layer (0 cm) or buried at 2 and 10 cm depths enclosed in nylon mesh bags and examined their viability for 42 months. In another study, the emergence pattern of four populations, each from these two locations, was evaluated under a rainfed environment in trays. In the mesh-bag study, rapid depletion of seed viability of S. oleraceous from the surface layer (within 18 months) and lack of seed persistence beyond two years from 2 and 10 cm depths were observed. In trays, S. oleraceous germinated 3 months after seeding in response to summer rains and there was progressive germination throughout the winter season reaching cumulative germination ranging from 22 to 29% for all the populations. In the mesh-bag study, it took about 30 months for the viability of seeds of R. rugosum to deplete at the surface layer and a proportion of seeds (5 to 13%) remained viable at 2 and 10 cm depths even at 42 months. Although fresh seeds of R. rugosum exhibit dormancy imposed due to the hard seed coat, a proportion of seeds germinated during the summer months in response to summer rains. Rapid loss of seed viability was observed for A. mexicana from the surface layer; however, more than 30% of the seeds were persistent at 2 and 10 cm depths at 42 months. Notably, poor emergence was observed for A. mexicana in trays and that was mostly confined to the winter season.

Effect of bioactive compounds released from Brassicaceae defatted seed meals on bacterial load in pig manure

Animal manure application to soils is considered to be one of the main cause of antibiotic and bacterial pathogen spread in the environment. Pig livestock, which is the source of one of the most used fertilizer for cultivated land, is also a hotspot for antibiotics and antibiotic-resistant bacteria. Besides harsh chemical and physical sanitization treatments for the abatement of antibiotics and bacterial load in livestock waste, more sustainable and environmentally friendly strategies need to be considered. In this context, the use of natural substances which are proved useful for pest and disease control is currently under exploration for their role in the reduction of bacterial pathogen population. Among these, plants and derived products from the Brassicaceae family, characterized by the presence of a defensive glucosinolate-myrosinase enzymatic system, have been successfully exploited for years in agriculture using the so-called biofumigation technique against crop diseases. Although the application of biofumigation to suppress a range of soil borne pests has been well documented, no studies have been examined to reduce bacterial population in animal waste. In the present study, the release and the antibacterial activity of bioactive compounds deriving from different Brassicaceae defatted seed meals against pathogens and bacterial population in pig manure is addressed. Rapistrum rugosum and Brassica nigra defatted seed meals were found to be the most active products against tested pathogens and able to significantly reduce the bacterial load in the manure.

Sown Wildflowers Enhance Habitats of Pollinators and Beneficial Arthropods in a Tomato Field Margin.

We evaluated the capacity of selected plants, sown along a processing tomato field margin in central Greece and natural vegetation, to attract beneficial and Hymenoptera pollinating insects and questioned whether they can distract pollinators from crop flowers. Measurements of flower cover and attracted pollinators and beneficial arthropods were recorded from early-May to mid-July, during the cultivation period of the crop. Flower cover was higher in the sown mixtures compared to natural vegetation and was positively correlated with the number of attracted pollinators. The sown Glebionis coronaria, Coriandrum sativum, Anethum graveolens, and Fagopyrum esculentum attracted mainly wild bees, which were the most abundant pollinating insects. In the natural vegetation, Rapistrum rugosum attracted mainly honeybees, while Asteraceae, Convolvulaceae, and Apiaceae species attracted wild bees. Beneficial arthropod abundance and diversity were higher in the sown mixture. Tomato flowers were visited by a small number of wild bees. Their number was not affected by the distance from the field margin, indicating no distraction effect from the sown or natural vegetation flowering plants. Our results suggest that selected flowering plants can improve the field margin habitats for pollinating insects and beneficial arthropods, but more work is needed to elucidate the effect on crop pollination.

Agricultural Weed Assessment Calculator: An Australian Evaluation.

Weed risk assessment systems are used to estimate the potential weediness or invasiveness of introduced species in non-agricultural habitats. However, an equivalent system has not been developed for weed species that occur in agronomic cropland. Therefore, the Agricultural Weed Assessment Calculator (AWAC) was developed to quantify the present and potential future adverse impact of a weed species on crop production and profitability (threat analysis), thereby informing or directing research, development, and extension (RDE) investments or activities. AWAC comprises 10 questions related primarily to a weed’s abundance and economic impact. Twenty weed species from across Australia were evaluated by AWAC using existing information and expert opinion, and rated as high, medium, or low for RDE prioritization based on total scores of 70 to 100, 40 to <70, or <40, respectively. Five species were rated as high (e.g., Lolium rigidum Gaud.), eight were rated as medium (e.g., Conyza spp.), and seven were rated as low (e.g., Rapistrum rugosum L.). Scores were consistent with the current state of knowledge of the species’ impact on grain crop production in Australia. AWAC estimated the economic or agronomic threat of 20 major or minor agricultural weeds from across Australia. The next phase of development is the testing of AWAC by weed practitioners (e.g., agronomists, consultants, farmers) to verify its utility and robustness in accurately assessing these and additional weed species.

Regeneration capacity after exposure to freezing in wild oat (Avena ludoviciana Durieu.) and turnipweed (Rapistrum rugosum (L.) All.) in comparison with winter wheat

Wild oat (Avena ludoviciana Durieu.) and turnipweed (Rapistrum rugosum (L.) All.) are the most important annual weed species of winter wheat (Triticum aestivum L.) in the Khorasan Razavi province of Iran. This study investigated freezing tolerance in wheat (cv. Mihan) and these two weeds based on electrolyte leakage (EL), survival (SU), regrowth characteristics and maximum photochemical efficiency of photosystem (PS) II (F'v/F'm). Significant differences in EL% at freezing temperatures were noted between these plant species. By decreasing the freezing temperatures, EL% of the leaf in all three plants was increased. The lowest and the highest temperature causing 50 % EL (TEL50) of leaves belonged to wild oat (−16.6℃) and wheat (−15℃), respectively. At a temperature of -12℃, SU% of wheat and turnipweed decreased by 15 % and 20 % compared to the SU% at 4℃, respectively. However, the decrease in SU% in wild oat from 4℃ to −12℃ was not significant. Lethal temperature for 50 % SU (LT50su) of wheat, wild oat, and turnipweed was −13.7, −14.3, and −13.5℃, respectively, and there was no significant difference between wheat and turnipweed. A general trend observed in our study was that species with higher freezing tolerance scores had a higher regrowth capacity. During the first 24 h after the freezing treatment, the F'v/F'm levels in wheat, wild oat, and turnipweed decreased by 33 %, 33 %, and 28 %, respectively, compared to before the freezing stress. Therefore, the presence of these weeds in wheat fields after freezing stress will be possible. Under optimal conditions and lack of integrated weed management programs, these weeds, especially wild oat, will emerge, set seeds and enrich the soil seed bank and thereby continue to be a problem in the cold climates of Iran, especially in the Khorasan Razavi province. Winter weed management using tillage, non-successive planting of annual winter crops, and crop rotation will reduce the dispersal of these weeds.

Effect of emergence time on growth and fecundity of Rapistrum rugosum and Brassica tournefortii in the northern region of Australia

Weeds from Brassicaceae family are a major threat in many crops including canola, chickpea, cotton and wheat. Rapistrum rugosum (L) All. and Brassica tournefortii Gouan. are two troublesome weeds in the northern region of Australia. In order to examine their phenology of these weeds, a pot study was conducted in 2018 at the Research Farm of the University of Queensland, Gatton campus with two populations sourced from high (Gatton) and medium (St George) rainfall areas of the northern grain region of Australia. Planting was carried out monthly from April to September, and the growth, flowering and seed production were evaluated. Maximum growth and seed production were observed in weeds planted in April, compared to other planting dates. Biomass of R. rugosum and B. tournefortii was reduced by 85% and 78%, respectively, as a result of the delay in planting from April to July. R. rugosum and B. tournefortii produced more than 13,000 and 3500 seeds plant−1, respectively, when planted in April and seed production was reduced by > 84% and > 76% when planted in July. No significant differences were observed between populations of both weeds for plant height, number of leaves and biomass, however, the medium rainfall population of R. rugosum produced more seeds than the high rainfall population when planted in April. The results of this study suggest that, although R. rugosum and B. tournefortii were able to emerge in a wider time frame, the growth and seed production were greatest when both weeds were planted in April and there was concomitant reduction in growth attributes when planted in the subsequent months, indicating that management of these weeds early in the cropping season is a prerequisite to population reduction and the mitigation of crop yield losses.

Emergence and germination response of Sonchus oleraceus and Rapistrum rugosum to different temperatures and moisture stress regimes

AbstractSonchus oleraceus and Rapistrum rugosum are two rapidly emerging weeds of the northern grain region of Australia. To understand the ability of these weeds regarding their germination response to temperature and different soil moisture regimes, experiments were undertaken on the germination of these weeds at varying osmotic potential and temperature regimes. The experiment was conducted as a split‐plot design with alternating day/night temperature regimes (15/5, 20/10, 25/15 and 30/20°C) as a main plot and osmotic potential regimes (0.0, −0.1, −0.2, −0.4, −0.6, −0.8 and −1 MPa) as a subplot. At different temperature regimes, there was 65–91% germination of S. oleraceus in water (0 MPa). There was 0–4% germination at −0.8 MPa and no germination at −1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of S. oleraceus based on a sigmoid regression model ranged from −0.38 to −0.48 MPa. There was 33–81% germination of R. rugosum in distilled water (0 MPa), 1–3% germination at −0.8 MPa and no germination at −1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of R. rugosum based on a sigmoid model ranged from −0.26 to −0.54 MPa. Results of the study were related to the emergence pattern of weeds during field survey and soil moisture profiles estimated by the Australian Landscape Water Balance Model and explain the emergence of these weeds outside the normal seasonal window of prevalence as a response to changes in weather.